Math Trig

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Suppose that X is an angle in standard position and that X' is it's reference angle. If cosX = -4/ squareroot of 17. find the exact value of cosX'

is it 4/square root of 17?

  • Math Trig -

    yes, X' would be in quadrant I, so its cosine would be positive.
    cos X' = 4/√17

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